Characteristic length of a Holographic Superconductor with dd-wave gap

After the discovery of the $s$-wave and $p$-wave holographic superconductors, holographic models of $d$-wave superconductor have also been constructed recently. We study analytically the perturbation of the dual gravity theory to calculate the superconducting coherence length $\xi$ of the $d$-wave holographic superconductor near the superconducting phase transition point. The superconducting coherence length $\xi$ divergents as $(1-T/T_c)^{-1/2}$ near the critical temperature $T_c$. We also obtain the magnetic penetration depth $\lambda\propto(T_c-T)^{-1/2}$ by adding a small external homogeneous magnetic field. The results agree with the $s$-wave and $p$-wave models, which are also the same as the Ginzburg-Landau theory.Comment: last version, 10 pages, accepted by PR

Constructing Confidence Intervals of the Summary Statistics in the Least-Squares SROC Model

The accuracy of a diagnostic test is often evaluated with the measures of sensitivity and specificity, and the joint dependence between these two measures is captured by receiver operating characteristic (ROC) curve. To combine multiple testing results from studies that are assumed to follow the same underlying probability law, a smooth summary receiver operating characteristic (SROC) curve can be fitted. Moses, Shapiro, and Littenberg (1993) proposed a least-squares approach to fit the smooth SROC curve, and the variances of the estimated parameters were derived by ignoring the variance of the independent variable. Since the independent variable was in fact random, the variances were likely underestimated. Hence we propose another way to estimate the variances of the statistics of interest, and use a real example to demonstrate the differences. We also perform a simulation study to examine these two approaches. The results suggest that the least squares estimates of the coefficients are biased, and that the averaged confidence coverage is not equal to its nominal level, regardless of the methods. While Moses et al.\u27s method tends to underestimate the confidence interval, our method sometimes overestimates the interval, depending on the ratio of the intra-study variation over the inter-study variation. Our estimation of the variances appears to be slightly better than the method proposed by Moses et al. because the coverage probability of the confidence interval is closer to the nominal level

Effect of mesenchymal stem cell transplantation on behavior and structural changes in myelin in experimental rat autoimmune encephalomyelitis

Purpose: To investigate the effect of bone marrow mesenchymal stem cell (BM-MSC) transplantation on behavior and structural changes in myelin of experimental autoimmune encephalomyelitis (EAE) in rats.Methods: Wistar rats were randomly assigned to normal control, EAE, placebo injection treatment, and MSCs treatment. EAE, placebo injection treatment and MSCs treatment groups were further divided into six groups, i.e., 1-day, 3-day, 7-day, 14-day, 21-day, and 28-day post-onset. Changes in the diseasestatus of the rats and structural changes in myelin at different time points were assessed with silver staining.Results: Behavioral changes peaked between 13 to 17 days post-immunization (71.90 % incidence), while disease symptoms peaked between 3 and 5 days after onset, were sustained for about 7 days, and then eased gradually thereafter. The highest therapeutic scores and the entire course of the disease in EAE and placebo treatment groups were not significantly different (p > 0.05). However, in MSC treatment group, these parameters were significantly lower than in the above two groups (p < 0.05). In EAE and placebo treatment groups, myelin sheath lesions were obvious from day 3 to 7 but on day 14, the number of myelin sheath fragments decreased significantly. Recovery at different time points was also better than those in EAE and placebo treatment groups.Conclusion: MSC transplantation shortens the course of EAE, and also reduces its severity. Thus, it has some prospects for use in the management of EAE.Keywords: Bone marrow mesenchymal stem cells, Autoimmune encephalomyelitis, Transplantation, Myeli

Why a local moment induces an antiferromagnetic ordering: An RVB picture

Based on a Gutzwiller projected BCS wavefunction, it is shown that a local S=1/2 moment is present around a vacancy site (zinc impurity) in a form of staggered magnetic moments, which is a direct consequence of the short-ranged resonating-valence-bond (RVB) pairing in the spin background.Comment: 4 pages, 3 figure